1. Field of the Invention
The present invention relates to a single-substrate-heat-processing apparatus and method for a semiconductor process, which perform a process such as annealing, film formation, etching, oxidation, or diffusion. The term xe2x80x9csemiconductor processxe2x80x9d used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
2. Description of the Related Art
In the process of manufacturing semiconductor devices, several types of heat-processing apparatuses are used for subjecting target substrates, such as semiconductor wafers, to a semiconductor process, such as annealing, film formation, etching, oxidation, or diffusion. A single-substrate-heat-processing apparatus, which handles wafers one by one, is known as one of these heat-processing apparatuses. The single-substrate-heat-processing apparatus allows a heat process to be relatively easily performed with a high planer uniformity on a wafer, even when the heat process requires the process temperature to be raised and lowered quickly. For this reason, the single-substrate-heat-processing apparatus has become popular, as the size of wafers has been larger, and the size of semiconductor devices has been smaller.
The process conditions, e.g., a process gas, a process temperature, and a process pressure, employed in the single-substrate-heat-processing apparatus largely change depending on the processing steps. For example, when a tantalum oxide film (Ta2O5), which recently attracts attention as a film with good insulating characteristics, is to be formed, heat-processing is performed in deposition, reformation, and crystallization of the film, and different process conditions are respectively employed in these processing steps.
In the manufacture of semiconductor devices, an increase in throughput is an important object in order to increase the mass productivity. As the cost necessary for maintaining the heat-processing apparatus is very high, it is required to reduce the number of units to be installed as small as possible. Under these circumstances, it has been proposed to perform similar processing steps, e.g., reformation and crystallization described above, continuously in a single heat-processing apparatus. Sometimes, however, the two processing steps have largely different process temperatures, like the processing steps of reformation and crystallization do. In this case, it takes time to change, particularly to increase, the temperature of the wafer. This decreases the throughput.
As a single-substrate-heat-processing apparatus, one with a structure that uses a heating lamp disposed under the worktable as a wafer heating source is known. This structure is advantageous in that it can increase the wafer temperature increase speed, while it is disadvantageous in that the window for transmitting light from the lamp therethrough is fogged from inside to likely decrease the heat efficiency and planar uniformity of heating. Therefore, depending on the contents of the process, an apparatus of this type is not appropriate as a mass-production apparatus.
In the most general single-substrate-heat-processing apparatus, a resistance heater disposed in the worktable is used as a wafer heating source. This structure is advantageous in that it can perform stable heating, while it is disadvantageous in that the wafer temperature increase rate decreases. In other words, it takes a comparatively long period of time since the amount of power to be supplied to the resistance heater is increased until the worktable and wafer reach a desired temperature.
It is an object of the present invention to provide a single-substrate-heat-processing apparatus and method for a semiconductor process, which can perform a plurality of, e.g., two, processes with different process temperatures continuously and quickly.
According to a first aspect of the present invention, there is provided a processing method in a single-substrate-heat-processing apparatus for a semiconductor process, the apparatus including a hermetic process chamber, a worktable with a support surface where a target substrate is to be placed in the process chamber, and a heater disposed to heat the target substrate through the support surface, the method comprising the steps of:
placing the target substrate on the support surface;
subjecting the target substrate to a first process at a first process temperature and a first process pressure while heating the target substrate on the support surface with the heater; and
subjecting the target substrate to a second process at a second process temperature and a second process pressure while heating the target substrate on the support surface with the heater, the first and second process pressures being different from each other and the first and second process temperatures being different from each other,
wherein in the first and second processes, the heater is set at preset temperatures substantially equal to each other, and a pressure in the process chamber is set at the first and second process pressures, such that a density of a gas present between the support surface and the target substrate is changed by using the pressure in the process chamber as a parameter, and thus a heat transfer rate between the support surface and the target substrate is changed, thereby setting the target substrate at the first and second process temperatures.
According to a second aspect of the present invention, there is provided a processing method of performing a first process of reforming a metal oxide film on a target substrate and a second process of crystallizing the metal oxide. in this order, in a single-substrate-heat-processing apparatus for a semiconductor process, the apparatus including a hermetic process chamber, a worktable with a support surface where the target substrate is to be placed in the process chamber, and a heater disposed to heat the target substrate through the support surface, the method comprising the steps of: placing the target substrate on the support surface;
subjecting the target substrate to the first process at a first process temperature and a first process pressure while heating the target substrate on the support surface with the heater; and
subjecting the target substrate to the second process at a second process temperature and a second process pressure while heating the target substrate on the support surface with the heater, the second process pressure being higher than the first process pressure, and the second process temperature being higher than the first process temperature,
wherein in the first and second processes, the heater is set at preset temperatures substantially equal to each other, and a pressure in the process chamber is set at the first and second process pressures, such that a density of a gas present between the support surface and the target substrate is changed by using the pressure in the process chamber as a parameter, and thus a heat transfer rate between the support surface and the target substrate is changed, thereby setting the target substrate at the first and second process temperatures.
According to a third aspect of the present invention, there is provided a single-substrate-heat-processing apparatus for a semiconductor process, comprising:
a hermetic process chamber;
a worktable with a support surface where a target substrate is to be placed in the process chamber;
a heater disposed to heat the target substrate through the support surface;
a gas supply system for supplying a process gas into the process chamber;
a gas exhaust system for vacuum-exhausting an interior of the process chamber; and
a controller for controlling the apparatus, the controller being adapted to set the heater at preset temperatures substantially equal to each other, and to set a pressure in the process chamber at first and second process pressures different from each other, such that a density of a gas present between the support surface and the target substrate is changed by using the pressure in the process chamber as a parameter, and thus a heat transfer rate between the support surface and the target substrate is changed, thereby setting the target substrate on the worktable at first and second process temperatures different from each other.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.